The researchers say these parasites commonly infect salmon raised in farms, but also attack young wild pink salmon that swim nearby. Their research suggests that if these outbreaks continue, then local populations of wild pink salmon will all but disappear."

"Fish Farms Drive Wild Salmon Populations Toward Extinction". ScienceDaily. Dec. 16, 2007 - "ScienceDaily (Dec. 16, 2007) — Parasitic sea lice infestations caused by salmon farms are driving nearby populations of wild salmon toward extinction. The results show that the affected pink salmon populations have been rapidly declining for four years. The scientists expect a 99% collapse in another four years, or two salmon generations, if the infestations continue.

The researchers, from the University of Alberta and elsewhere, studied the number of juvenile fish that become infested with the parasitic lice as they swim past commercial fish pens on their way from inland rivers to the ocean. In laboratory work, they tested the parasites’ effects on fish mortality. Then they used mathematical models to estimate the overall impact of fish farming on wild stocks.

Depending on when the young salmon pass by the fish pens, up to 95 percent receive lethal parasite exposure, they said. They report their findings today in The Proceedings of the National Academy of Sciences."